[ M9 ] 



but at a medium about half its weight *. Dodor Woodward 

 found that a fprig of common fpearmint, a plant that thrives 

 moft in moift foils, weighing only 28,25 grs. paffed through 

 it 3004 grs. in 77 days, between July and Odober, that is, 

 fomewhat more than its own weight each day. He did more, 

 for he found that in that fpace of time the plant increafed 

 17 grs. in weight, and yet had no other food but pure rain 

 water. But he alfo found that it increafed more in weight 

 when it lived on fpring- water, and ftill more when its food' 

 was Thames water f. From whence we may deduce that 

 graffes and corn, during the time of their growth, abforb 

 about one half their weight of water each day if the weather 

 be favourable. Secondly, That the water they thus pafs nou- 

 rilhes them merely as water, without taking any foreign fub- 

 flance into the account ; for 3000 grs. of rain-water, in Dodor 

 Woodward's experiment, afforded' an increafe of 17 grains, 

 whereas by Margraaff's experiments 5760 grs. of that water 

 contain only ^ gr. of earth J. But, Thirdly, It alfo follows, 

 that water contributes ftill more to their nourifhment when 

 it conveys to them earthy and faline particles, as fpring and 

 Thames waters do. 



The manner in which pure water contributes to the nou- 



rifhment of plants, befides the fervice it renders them in diftri- 



buting the nutritive parts throughout their whole flrudure, 



and forming, itfelf, a conftituent part of all of them, may be 



underftood from modern experiments. Dodor Ingenhouz and 



Mr. 

 t 



* I Hales, 9. 10. 15. t a Phil. Tranf. Abr. 716. % 2 Margr. 6. 70^ 



